The conventional portable computing device, such as a laptop computer, a PDA, or a wireless telephone, includes a Liquid Crystal Display (LCD) display for presenting information to the user, and a keyboard or keypad for facilitating data entry by the user. Typically, the LCD display comprises a transmissive LCD panel, and a backlight for enhancing the visibility of the information presented on the LCD panel. The intensity of the light produced by the LCD backlight is set by the manufacturer such that the information presented on the LCD panel is clear at moderate ambient light levels. However, this factory setting often renders the LCD panel difficult to read in dim light (because the backlight is too bright, thereby effectively “blinding” the user of the portable computing device) and strong ambient light (because the backlight is too dim).
In some implementations, instead of a transmissive LCD panel, the LCD display comprises a reflective or a transreflective LCD panel, and a backlight for enhancing the visibility of the information presented on the LCD panel. Due to the reflective nature of the LCD panel, the clarity of the information presented on the LCD panel is clearest in strong ambient light. Further, the intensity of the light produced by the LCD backlight is set by the manufacturer such that the information presented on the LCD panel is clear at moderate ambient light levels. However, this factory setting often renders the LCD panel difficult to read in dim ambient light because the backlight in effect “blinds” the user of the portable computing device.
Similarly, the keyboard or keypad on such devices typically includes a set of keys, and a backlight for enhancing the visibility of the information presented on the surface of the keys. The intensity of the light produced by the keyboard/keypad backlight is set by the manufacturer such that the information presented on the keys is clear in moderate ambient light levels. However, this factory setting often renders the keys difficult to read in dim ambient light because the backlight “blinds” the user of the portable computing device.
Therefore, there is a need for a portable computing device whose LCD display (and optionally its keyboard/keypad) is readable in strong, moderate and dim ambient light.